Continuously variable transmissions are known, for example, from European patent publication 0,451,887 as well as from U.S. Pat. No. 5,514,050. In such systems, the change of gear ratio of the vehicle transmission is effected with a specific adjusting speed. In U.S. Pat. 5,514,050, a manual actuation for such a continuously variable transmission is disclosed. In this so-called lever-positioning operation, the driver is afforded the possibility to adjust the continuously variable transmission by actuating an actuating device. Especially, it is here provided that the adjustment of the gear ratio takes place at a constant rate of change.
The speed at which the gear ratio is changed should be adapted optimally to the driver command in order that the driving performance of a vehicle having a continuously adjustable transmission is realized so as to be more attractive for the driver of the vehicle. For a normal acceleration operation of the vehicle, the driver expects an increase of the engine rpm to be a function of the vehicle speed as the driver is already accustomed to from a manual transmission or from a conventional step automatic. When the accelerator pedal is pressed down rapidly such as for a kickdown in a step automatic, a higher motor capacity should be made available immediately, that is, the motor rpm should increase in a relatively short time span. In addition, the driver would like to utilize the braking action of the motor during overrun operation and during braking operation.
Furthermore, the influence of a driver evaluation characteristic variable should be considered.